; Outbound domestic calls.
; NXX-XXX-XXXX calls in the US.
[outbound-domestic]
exten => _NXXNXXXXXX,1,Dial(${OUTBOUNDDOMESTICTRUNK}/${EXTEN:1})
; Once call is over, fast busy
exten => _1NXXNXXXXXX,2,Congestion()
; If call fails (1+101 = 102), monkeys
exten => _1NXXNXXXXXX,3,Playback(tt-monkeys)


I think the SIP provider here requires 1+NXX-NXXXXXX dialing format. If I change the above to this the follow, it fails:

; Outbound domestic calls.
; NXX-XXX-XXXX calls in the US.
[outbound-domestic]
exten => _NXXNXXXXXX,1,Dial(${OUTBOUNDDOMESTICTRUNK}/${EXTEN:1})
; Once call is over, fast busy
exten => _NXXNXXXXXX,2,Congestion()
; If call fails (1+101 = 102), monkeys
exten => _NXXNXXXXXX,3,Playback(tt-monkeys)

I don't want to have to dial 1+. How can I have this 1 automatically added for outgoing calls?